Introduction


  • This lesson will take you through adjusting Anti-aliasing parameters using the V-Ray Quick Settings
  • The information centers around the Image Sampler render settings and how it’s effected by Motion Blur and Depth of Field
  • This lesson topic covers three learning cycles in one presentation and is approximately 30 minutes in length
  • Lesson covers all 3 Learning Cycles for the Lesson Topic – Lecture, Demonstration, and Activity

 

 

Contents


Overview
Available Materials
Lecture
Demonstration
Activity                                                    
Additional resources           
                                                                                                                                                                                                                                          

Overview


Goal: By the end of this lesson you will have the necessary knowledge to optimize the antialiasing of camera effects like Depth of Field and Motion Blur

Objective – We will learn how to adjust the Anti-Aliasing settings to our 3D scene to get better render results and render times when adding Motion Blur and/or Depth of Field                                  

Outcome – You will understand how image sampling works within V-Ray to reduce render noise when using Depth of Field effects or Motion Blur to your scene

 

 


Available materials


To set up the lesson follow the links below and download all available materials.

Lesson plan download
Presentation (Lecture) download
Demonstration tutorial 1 download
Demonstration tutorial 2 download
Scenes & Assets download

Lecture



1. Terminology

 

Here are some terms to be aware of when thinking about Image Sampling
  • Sampling
    • Gathers information from the rays to determine what each pixel will look like in the render
  • Anti-aliasing
    • A blending/blurring of pixel information based on sampling differences to produce a cleaner render particularly on diagonal/curved areas of a render, or where there is a difference in pixel colors/values
  • Depth of Field
    • The distance between the closest and farthest objects in a scene that appear sharp (clear) in an image
  • Motion Blur
    • The apparent streaking of a moving object in an image due to movement faster than the camera shutter or a long exposure by the camera

 

2. Image Sampling


a) Depth of Field (DoF)

  • Primary Parameter to affect DoF is F-number
    • Also known as F-Stop or Aperture setting
  • The Focal Length also plays a role in determining how far the distance is between completely in focus and completely out of focus within the shot
  • Adjust the F-number will change the exposure of the shot
    • Lower numbers mean more light will be taken into the camera and the render will be brighter
    • Higher numbers mean less light makes it into the camera and the render will be darker

 

 


b) Motion Blur
  • Primary Parameter that affects Motion Blur is a camera’s Shutter Speed
    • Shutter Speed is how long the camera is open to expose the image sensor (or film) to capture an image
    • Measured in fractions of a second
    • Becomes Shutter Angle and Shutter Offset when using a cinema camera over a photography camera

 

 

c) V-Ray Quick Settings
 
  • The Studio Setup preset is useful for product design visualizations
    • The Manage Presets allows you to save the current settings into the V-Ray presets file or to load previously saved settings
    • The Settings buttons give you a quick way to jump to the render settings that apply to the area affected by the Quality sliders (GI, Shading, Anti-Aliasing)
    • The AA Slider Limit sets the top end (the far right) amount for the AA Quality slider

 

 


d) Render Elements
  • The Sample Rate pass shows us the difference in how samples are used when Depth of Field is added to our render camera
  • Dark blue means less samples are taken for the pixel. Red means the highest number of samples taken

 

 

Depth of Field Off

Depth of Field On

 


e) V-Ray Quick Settings AA Quality

  • The Anti-Aliasing Quality slider adjusts the Image Sampler’s Min Subdivs, Max Subdivs, and Noise Threshold
    • Min Subdivs determines the initial (minimum) number of samples taken for each pixel
    • Max Subdivs determines the maximum number of samples for a pixel
      • Remember the actual maximum number of samples is the square of this number (e.g. 4 subdivs produces a maximum of 16 samples)
      • Note that V-Ray may take less than the maximum number of samples, if the difference in intensity of the neighboring pixels is small enough.
  • Noise Threshold controls the noise amount

 

 


f) Anti-Aliasing for Depth of Field
  • The higher Max Subdivs and lower Threshold (from AA Quality) will improve the quality of your Depth of Field effect
  • A higher Shading Quality (Min shading rate) will put more rays to secondary shading effects and less towards primary AA rays (which affects Depth of Field)

 

 

Shading Quality: 6%
AA Quality: 1-4 Threshold: 0.02

Shading Quality: 6%
AA Quality: 1-12 Threshold: 0.005

 


g) Anti-Aliasing for Motion Blur

  • The noise in the motion blur is reduced with a higher Max subdivs amount
  • The Threshold value controls how many samples are used within the min/max range. The lower the threshold, the closer the samples get to the max amount

 

 

AA Quality Min/Max: 1/4 Threshold: 0.02

AA Quality Min/Max: 1/24 Threshold: 0.005

 

h) Progressive Sampler

When using the Progressive Sampler Engine the entire image is progressively refined over a number of passes

  • Built on the same path tracing tech. as V-Ray RT
  • Renders can be evaluated almost instantly
    • Great for Look Development or initial lighting setups
  • Max Render Time parameter allows render to keep refining until time limit is met
    • Great when you want to see how good the render will look after 1 or 2 minutes of calculating
    • Setting to 0 will allow the engine to keep refining until all samples are resolved to the best they can be
  • Takes some of the guess work out of setting sampling settings and relies purely on how much time you want to devote to each frame
  • Requires more memory because entire scene has to be loaded before rendering starts

 

  

  • Max. render time (min) set to 0.5 means render will continue to refine for 30 seconds
  • Higher Shading Quality means V-Ray spends more of the provided time calculating shading effects (with secondary rays) and less on camera effects (DoF or Motion Blur) with primary rays

 

 

Max render time: 0.5   Shading Quality: 3%
AA Quality: 100%  AA max subdivs: 100

Max render time: 0.5   Shading Quality: 100%
AA Quality: 100%  AA max subdivs: 100

 

 

  • The Reflect Render Element helps with seeing the difference with the Shading Quality
  • Setting the Noise Threshold to 0 will sample the entire image uniformly until either the Max subdivs or the Render time limit is reached

 

 

Shading Quality: 3%
AA Quality: 100%  AA max subdivs: 100

Shading Quality: 100%
AA Quality: 100%  AA max subdivs: 100

 

 

Conclusion



a) Depth of Field
  • The effect of having some things in our scene in focus and others out of focus
b) Motion Blur
  • The effect of objects being blurred or streaky when moving within the render
c) Sampling
  • Gathering information in the scene for each pixel in our render and tracing it back to the final image
d) Anti-Aliasing
  • A way to make our renders look better by using the information sampled from our scene
e) Secondary Rays                                                                                                                                          
  • The more we have in our scene, the better our Depth of Field and Motion Blur effects will look


Demonstration



Time to see it work!

Watch while I demonstrate how to adjust the Sampling settings of our render using the V-Ray Quick Settings (and the VRay section of the Maya Render Settings window) to produce high quality renders fast when using Depth of Field and Motion Blur on our camera.

 

              

Activity



Time to do it yourself!

Use the provided scene file to get a better understanding of image sampling and camera effects.
We have also provided a final scene for your reference.

 

 

Dialing in the right values

 a) Depth of Field demo/activity
 

Quick Settings – Studio Setup

  • No GI

Shading Quality at 6%

  • Min Shading Rate: 4

AA Quality at 48% (Slider Limit 50)

  • AA Min subdivs: 2
  • AA Max subdivs: 25
  • AA Noise Threshold: 0.002

Render Settings > Overrides > Camera

    • Depth of Field: Enabled
    • Aperture: 2.8
    • Focus distance: 74

 

 



 

 

 b) Motion Blur demo/activity

Quick Settings – Studio Setup

    • No GI

Shading Quality at 6%

    • Min Shading Rate: 4

AA Quality at 48% (Slider Limit 50)

    • AA Min subdivs: 2
    • AA Max subdivs: 25
    • AA Noise Threshold: 0.002

Render Settings > Overrides > Camera

    • Motion Blur: Enabled

 

 



 

 

c) Progressive demo/activity

Quick Settings – Studio Setup

    • No GI

Shading Quality at 100%

    • Min Shading Rate: 64

AA Quality at 100%

    • AA Max subdivs: 100
    • Noise Threshold: 0.005

 

 



 

                                                                                                                                                                                                                                             


 

Additional resources